1. Field of the Invention
The embodiment discussed herein relates to a semiconductor module.
2. Background of the Related Art
As one kind of semiconductor devices, semiconductor modules each provided with a plurality of semiconductor elements (switching elements), such as Insulated Gate Bipolar Transistor (IGBT) and power Metal Oxide Semiconductor Field Effect Transistor (MOSFET), are widely used. For example, switching, converting, or another function is implemented by connecting such semiconductor modules in parallel. Among such semiconductor modules, non-insulated semiconductor modules, which do not have an insulating function therein, have low inductance in the internal wiring, compared with insulated semiconductor modules.
A non-insulated semiconductor module has a gate terminal and a source terminal on its upper surface and a drain terminal on its lower surface. In addition, gate and source conductors are disposed together on the upper surface, a drain conductor is disposed on the lower surface, and these conductors are pressure connected from the upper and lower sides, so that the semiconductor module is electrically connected to outside (see, for example, Japanese Laid-open Patent Publication No. 07-312410).
As materials for switching elements, wide-bandgap semiconductor materials such as silicon carbide are used, instead of silicon. These materials enable the switching elements to have high voltage withstanding capability and achieve fast switching.
However, in a switching element made of a wide-bandgap semiconductor material, a body diode (parasitic diode) is internally formed in the switching element. When the switching element is turned off from on, a reverse voltage is applied, so that an electric current flows through the body diode. Therefore, in the case where such a switching element is used in the semiconductor module disclosed in Japanese Laid-open Patent Publication No. 07-312410, the on-resistance of the switching element increases. As a result, the switching element is heated and degraded, and thus the characteristics of the semiconductor module may be degraded.